I'm thinking since the notches are on both sides, there has to be a way eagletac gets the mode switching ring on.. maybe a tool shaped like this:
That goes into the head to unscrew it..
I've also found that the threading for the head goes all the way down past the heatsink.
I'm thinking if I dimple the metal head below the brass spring, I should be able to stick some needlenose pliers in there and unscrew it?